Mounting device for coated abrasive finishing articles

ABSTRACT

A reusable mounting device which includes a support member having a support pad ( 32 ) secured to a hollow cylindrical body ( 42 ) by way of a compression ring ( 46 ). The hollow body defines a recess which receives a nut ( 18 ) that is adapted to protrude through a central aperture in an abrasive disc ( 1 ) and includes an irregular surface ( 22 ) providing an interference fit between the nut and the aperture in the disc. The nut extends into the hollow cylindrical member and includes an internal threaded bore adapted for threadable engagement with a drive member ( 30 ) which forms a part of or is attached to a portable power tool.

This application is a 371 of PCT/US01/50905 filed Oct. 30, 2001 whichclaims benefit of 60/265,485 filed Jan. 31, 2001.

FIELD OF THE INVENTION

This invention relates generally to abrasive finishing articles and moreparticularly, to a mounting device for attaching coated abrasivefinishing articles to the drive member of a power tool.

DESCRIPTION OF THE PRIOR ART

The use of rotatably driven abrasive finishing articles and particularlycoated abrasive finishing articles such as discs is widespread andfamiliar in our industrial society. Traditionally, such an abrasive discis removably attached by way of a hub assembly including a disc supportpad to a power tool. When the hub is rotated, the disc rotates with itpermitting the moving disc abrasive surface to effectively finish thesurface of work pieces. A variety of hub structures have been used inthe prior art to secure the abrasive finishing disc to the power tool.

The earliest and very common of such structures includes a support padhaving a reinforced central aperture arranged to be engaged over thethreaded end of the rotary shaft of the power tool. The abrasivefinishing disc is placed on the flat surface of the pad and a flangednut is turned down onto the threaded end of the rotary shaft protrudingthrough the disc. When the nut is tightened, the flange lays flushagainst the abrasive surface of the disc and clamps the disc to thesupport pad.

This traditional mode of attaching the abrasive finishing disc to therotary power tool has two major disadvantages. The first of these isthat in engagement of the rotating finishing disc against the workpiece, a large amount of torque is imparted to the hub which tends totighten the nut onto the threaded shaft of the power tool making itquite difficult to remove the nut in order to replace the disc after itis spent and usually involves the use of tools. In many heavy industrialapplications, such abrasive discs have to be replaced quite often. As aresult, when considering the number of power tools which may be in useat any given time, there is an excessive amount of downtime necessitatedby such disc replacement. The second disadvantage is that the flange ofthe nut extends onto the above surface of the finishing disc and theworker must be quite careful to prevent the flange on the nut fromengaging the work piece which in most cases would impart damage to thework piece.

In order to avoid the problems above referred to, a quick releaseabrasive finishing disc hub was developed and is most clearly shown inU.S. Pat. Nos. 3,667,169 and 3,667,170. As is disclosed therein, anadapter is provided which engages the power tool shaft and the adapteris placed on a standard support pad. The adapter is typically adhered tothe back surface of the abrasive finishing disc and includes a raisedboss having a central aperture whose rim is turned inward and shaped toform a screw thread which receives the threaded end of a stud on or theend of the power tool shaft itself. This allows the user to attach orremove the abrasive disc to the power tool rather quickly. However,through the utilization of such devices, the attaching structure isdisposable along with the spent disc and therefore, increases the costof the materials used in the abrasive finishing process.

In view of the foregoing disadvantages of the prior art abrasivefinishing disc mounts, it is desirable to provide a mounting device forcoated abrasive finishing articles and particularly a coated abrasivefinishing disc which is reusable and will provide the ability to theuser to quickly and easily remove and mount abrasive finishing discsupon a portable power tool without the need for wrenches, screwdrivers,or other tools and without the attachment of any external adapters orother attachment devices directly to the abrasive finishing discs.

A typical attachment of the type above referred to for securing a coatedabrasive disc having a central aperture to the power tool with a nuthaving flange is shown by the patent to G. L. Bryson, U.S. Pat. No.2,699,020. An additional type of quick change structure in addition tothe patents above referred to which includes an adapter secured to theabrasive discs is shown by the patent to Field, U.S. Pat. No. 3,653,858.

SUMMARY OF THE INVENTION

A mounting apparatus for rotatably securing a coated abrasive finishingarticle to the drive member of a power tool which includes a supportmember and a nut adapted to extend through an aperture in the finishingarticle for engaging the finishing article with the power tool whichcomprises an outer irregular surface on the body of the nut which isadapted to engage an edge of the aperture through the finishing articlein an interference fit and a centrally disposed threaded bore forengagement with the power tool drive member, a support pad is provideddefining a centrally located aperture and a face to engage the abrasivefinishing article with the support pad having a reduced thickness regionadjacent and surrounding the aperture therethrough. The support memberfurther includes a hollow externally threaded cylinder having anoutwardly extending flange at one end thereof and a compression ring.The support pad is secured between the flange and the compression ringto secure the support pad upon the cylinder. The end of the cylinderhaving the flange defines a recess adapter to receive a flange extendingoutwardly from one end of the nut so that when assembled in operationalconfiguration, the flange on the nut is below the abrasive finishingarticle surface so that it cannot engage a work piece during use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an abrasive finishing disc assembledwith the mounting device of the present invention;

FIG. 2 is a partially exploded view of the structure as illustrated inFIG. 1;

FIG. 3 is a partially exploded view of an alternative embodiment of amounting structure in accordance with the present invention;

FIG. 4 illustrates an abrasive finishing disc with the nut of thepresent invention secured thereto;

FIGS. 5A, B and C illustrates three embodiments of an attachment nutconstructed in accordance with the principles of the present invention;

FIG. 6 illustrates in cross-section schematically one embodiment of asupport pad constructed in accordance with the principles of the presentinvention;

FIG. 7 illustrates an alternative embodiment of such a support pad; and

FIG. 8 illustrates yet another alternative embodiment of a support padconstructed in accordance with the present invention.

DETAILED DESCRIPTION

Referring now more particularly to FIG. 1 there is illustratedschematically in cross-section, a mounting device for coated abrasivediscs constructed in accordance with the principles of the presentinvention with a coated abrasive member secured thereon. As isillustrated in FIG. 1, the support member constructed in accordance withthe present invention is adapted to secure an abrasive finishing article10 in the form of a coated abrasive disc having a first surface 12 withabrasive finishing material thereon and a second uncoated surface 14 onthe opposite side thereof. The disc 10 defines an aperture 16 centrallydisposed therethrough. A nut 18 having a flange 20 extending outwardlyfrom one end thereof is pushed through the aperture in such a mannerthat an outer surface 22 having an irregular configuration forms asubstantially interference fit with the edge 24 of the aperture. As willbe described more fully herein below, the irregular surface may beformed by a plurality of alternating ridges and grooves which may takeany shape desired and preferably would be disposed parallel with theaxis 26 of the nut. The nut also defines a bore 26 therein which isinternally threaded to receive the threaded end 28 of a drive member 30which is adapted to be affixed to a power tool (not shown) but wellknown to those skilled in the art. A support pad 32 is provided and hasa surface 34 which engages the surface 14 of the abrasive disc 10. Thesupport pad also defines an aperture 35 centrally disposed therethrough.The surface 34 of the support pad 32 immediately adjacent to the opening35 therethrough has a reduced thickness which is adapted to receive asecond flange 36 on a cylinder 42. The support pad 32 in accordance witha preferred embodiment of the present invention useful with smallerdiscs includes a semi-rigid member 38 which may be formed of plastichaving an elastomeric material 40 secured thereto with the elastomericmaterial 40 engaging the surface 36 of the abrasive disc 10 oralternatively, may be formed solely of elastomeric material. The supportmember further includes the hollow cylindrical member 42 having anexternally threaded surface 44. Threadably secured upon the externalsurface 44 is a compression ring 46. As is shown, the support pad 32 isdisposed upon an outwardly extending lip or flange 36 of the cylindricalmember 42. It should be apparent to those skilled in the art that thesupport pad 32 is captured between the flange 48 and the compressionring 46. It should also be noted that the flange 36 is received withinthe reduced thickness area of the support pad 32. The end of thecylinder adjacent the flange 36 defines a recess which is adapted toreceive the flange 20 on the nut 18 so that when assembled on themounting device, the flange 20 is below the abrasive finishing articleson the surface 12 of the disc 10 to preclude the flange coming intocontact with the work piece.

If desired, an additional backing member or disc 50 may be providedalong with the support pad 32 to provide additional rigidity. Dependingupon the application and the rigidity desired, the additional backupdisc 50 may be constructed of metal. Under those circumstances, it mayalso be desirable to provide an elastomeric washer 52 which is seatedbetween the metal disc 50 and the compression ring 46 to assist insecuring the back pad and supporting discs in proper relation to providethe support desired for the abrasive finishing disc 10.

As is further shown in FIG. 1, the drive member 30 includes a flange 54which seats against a surface 56 of the cylinder 42. The cylinder 42defines an opening 58 through which the drive member extends. Theportion 60 of the drive member extending through the opening 58 carriesan O-ring 62 which provides frictional engagement with the opening 58.Through the frictional engagement, the support member is retained uponthe drive member 30 during the time the coated abrasive disc 10 isdetached for removal and replacement after it is spent. It is animportant feature of the present invention that the support member isnot in any way threadably attached to the drive member 30. It should berecognized that the support pad 32 along with the abrasive disc 10 isrotatable with respect to the drive member 30. As a result, the abrasivedisc 10 and the support pad 32 may be rotated by hand to attach the nut18 to the threads 28 on the end of the drive member 30. Also, thetogether (or simultaneously) support pad along with the disc may berotated in the opposite direction by hand once the disc is spent toremove the nut 18 from the threaded end 28 of the drive member 30.

Referring now, more particularly, to FIG. 2, the apparatus in accordancewith the present invention is illustrated in partially explodedschematic fashion without the abrasive disc. The same reference numeralsare utilized for the same parts as set forth in the description of FIG.1. By reference to FIG. 2, the recess on the end of the cylinderadjacent the flange 36 is more clearly shown at 64. The flange 20 on thenut 18 seats within the recess 64 with the coated abrasive disc trappedbetween the flange 20 and the bottom of the recess 64 to thus cause theflange 20 to be positioned below the outer surface of the abrasive discso that it will not come into contact with the work piece. The irregularsurface 22 constructed as a plurality of alternating ridges and grooveswhich cut through the edge of the aperture 35 in the abrasive disc 10are more clearly illustrated in FIG. 2.

It should also become more clear from the illustration shown in FIG. 2that the only threaded engagement with the drive member 30 which isinterconnected to the power tool at any portion of the mounting memberis between the threads 28 on the drive member 30 and the internalthreads on the bore of the nut 18.

By referring now to FIG. 3, there is illustrated a partially explodedview similar to that of FIG. 2 but with a modified mounting deviceadapted for use with larger abrasive discs. As is shown in FIG. 3, ahollow cylindrical member 70 defines a recess or groove 72 therein whichreceives an O-ring 74. As is illustrated, a washer like member 76 isadhered to the cylindrical member 70 either by being physically attachedor the like and traps the O-ring 74 in place. The O-ring 74 engages thethreads which appear on the shaft 78 of the power tool spindle 80 andassists in holding the support member 82 on the power tool spindleduring the time the spent abrasive disc is being removed, discarded, andreplaced with a new abrasive disc. Also, the nut 84 used with thisembodiment is slightly larger and constructed to include a taperedsurface 86 which substantially mates with the recess 88 formed on thesurface of the cylindrical member 70 adjacent the flange 90 which isused to grip the support pad in place.

Referring now more particularly to FIG. 4, the cooperative relationshipbetween the abrasive disc 10 and the nut 18 is better illustrated. As isshown therein, the shank 92 of the nut 18 has formed thereon theirregular surface 22 in the form of alternating ridges and grooves whichpreferably are substantially parallel to the longitudinal axis of thenut 18. When the nut 18 is forced into place through the centralaperture formed in the abrasive disc 10, the ridges cut into the surfacedefining the central aperture in such a way that an interference fit isformed between the nut 18 and the central aperture in the abrasive disc10. The interference fit then provides the ability to turn the disc 10and at the same time, turn the nut 18 so that the threads formedinternally in the bore provided therein engage the threads 28 on thedrive member 30 thus, pulling the flange 20 on the nut 18 down and intothe recess 64 carrying with it that portion of the abrasive disc 10immediately surrounding the aperture through which the shank 92 has beenextended thereby clamping the disc 10 in place on the support pad 32 foruse. It should be understood that those skilled in the art that theabrasive disc 10 may be constructed of any coated abrasive material knowto those skilled in the art. For example, the disc 10 may be formed ofcloth, paper, vulcanized fiber, or the like.

Referring now, more particularly, to FIGS. 5A, B and C there isillustrated three different embodiments of nuts which could be used inaccordance with the principles of the present invention. In FIG. 5A, thenut having the alternating ridges and grooves is illustrated. In FIG.5B, an irregular surface is provided in the form of elastomeric cylindersurrounding the barrel of the nut below the flange. In FIG. 5C theirregular portion can be enlarged greatly with respect to the size ofthe aperture through the abrasive disc or may have ridges and groovesarranged in a manner other than parallel to the axis as shown oralternatively the area immediately below the flange may be enlarged to adiameter greater than the aperture in the disc to provide aninterference fit without any irregularities in the surface.

Referring now, more particularly, to FIG. 6, the support pad 32 is shownin greater detail and the reduced diameter area is shown more clearly at94. The plastic material of the support pad 32 as shown at 96 may be anytype of plastic material desired but preferably, would be molybdenumdisulfide filled nylon material.

As shown in FIG. 7, the support pad 98 could be formed totally of themolybdenum disulfide filled nylon with the reduced diameter section 100thereof adjacent the opening 102 therethrough. As is evident in thestructure shown in FIG. 7, the surface 104 of the support pad 98 doesnot have a surface formed of an elastomeric material or any othermaterial which could provide a gripping surface with regard to thecoated abrasive disc. The pad of the type shown in FIG. 7 would beutilized with a larger coated abrasive disc than would the pad in FIG.6.

There is shown in FIG. 8 yet another pad 106 which is much thinner butalso may be formed of a suitable plastic material which has been formedto provide the reduced diameter portion 108.

There has thus been disclosed a mounting device for a coated abrasivefinishing article in the form of a coated abrasive disc which may bereused indefinitely and which permits easy attachment and detachment byhand without the use of tools for the replacement of spent abrasivediscs. The mounting device is constructed in such a manner that the nutfor attaching the abrasive disc to the support member is recessed belowthe surface of the abrasive disc and thus will not contact a work pieceduring use.

1. A mounting apparatus for rotatably securing a coated abrasivefinishing article (10) having a first surface (12) coated with abrasivematerial and a second uncoated surface (14) and defining a centrallylocated first aperture (16), having an edge (24) therethrough, to apower tool drive member (30) which includes a support member having asupport pad (32) for engaging said second surface, a nut (18) having abody extending through said aperture for threadably engaging said powertool and said body having an outwardly extending first flange (20) atone end engaging said first surface characterized by: the body of saidnut having (a) an outer irregular surface (22) adapted to engage saidedge (24) of said aperture (16) in a substantially interference fit, and(b) a centrally disposed threaded bore (26) for engagement with saidpower tool drive member (30); the support pad defining a centrallylocated second aperture (35) therethrough and having a face (34) forengaging said second surface, said pad having a reduced thickness regionadjacent and surrounding said second aperture; and said support memberfurther including a hollow externally threaded cylinder (42) having asecond outwardly extending flange (36) at one end thereof and acompression ring (46) defining internal threads, said second flangebeing received within said reduced thickness region and said compressionring being threadably received on said external threaded cylinder tosecure said support pad upon said cylinder, said one end of saidcylinder defining a recess (64) for receiving said first flange so thatwhen assembled in operational configuration on said power tool, saidflange is below said first surface so as not to engage a work piece. 2.A mounting apparatus as defined in claim 1 wherein said face of saidsupport pad is formed of material adapted to provide frictionalengagement with said second surface.
 3. A mounting apparatus as definedin claim 2 wherein said material is an elastomeric material.
 4. Amounting apparatus as defined in claim 1 wherein said support pad isformed of semi-rigid material.
 5. A mounting apparatus as defined inclaim 1 wherein said outer irregular surface is formed by a plurality ofalternating ridges and grooves.
 6. A mounting apparatus as defined inclaim 5 wherein said outer irregular surface is disposed only at saidone end adjacent said flange.
 7. A mounting apparatus as defined inclaim 6 wherein said ridges are substantially parallel to the axis ofsaid body and when said nut is inserted through said first aperture saidridges cut into said edge of said first aperture to form saidsubstantially interference fit.
 8. A mounting apparatus as defined inclaim 1 wherein said support member further includes at least oneremovable disk (38, 50) disposed between said support pad and saidcompression ring to provide greater rigidity to said support member. 9.A mounting apparatus as defined in claim 8 wherein said at least onedisk is formed of a semi-rigid plastic material.
 10. A mountingapparatus as defined in claim 9 wherein said material is molybdenumdisulfide filled nylon.
 11. A mounting apparatus as defined in claim 8which further includes at least one additional disk formed of metal. 12.A mounting apparatus as defined in claim 11 wherein said metal disk ispositioned for engagement by said compression ring and which furtherincludes an elastomeric washer (52) disposed between said compressionring and said metal disk.
 13. A mounting apparatus as defined in claim 1which further includes an elastomeric member (62, 72) for interfacingbetween said power tool drive member and said cylinder to assist inretaining said support member on said drive member during the timeabrasive finishing articles are changed.
 14. A mounting apparatus asdefined in claim 13 wherein said elastomeric member is carried by saidhollow cylinder.
 15. A mounting apparatus as defined in claim 13 whereinsaid elastomeric member is carried by said drive member.
 16. A mountingapparatus as defined in claim 1 wherein said hollow cylinder includes athrough bore defining a recess adjacent the other end thereof, and an“O” ring seated within said recess for engaging the drive member toassist in retaining said support member on said drive member when coatedabrasive finishing articles are changed.